JP2011199183A - Rare earth magnet and rotary machine - Google Patents

Rare earth magnet and rotary machine Download PDF

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JP2011199183A
JP2011199183A JP2010066752A JP2010066752A JP2011199183A JP 2011199183 A JP2011199183 A JP 2011199183A JP 2010066752 A JP2010066752 A JP 2010066752A JP 2010066752 A JP2010066752 A JP 2010066752A JP 2011199183 A JP2011199183 A JP 2011199183A
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rare earth
earth magnet
magnet
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rich phase
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JP5471678B2 (en
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Masashi Miwa
将史 三輪
Yasuyuki Kawanaka
康之 川中
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TDK Corp
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Abstract

PROBLEM TO BE SOLVED: To provide a rare earth magnet with excellent corrosion resistance.SOLUTION: The rare earth magnet 100 includes a crystal particle group 4 of an R-Fe-B alloy containing a rare earth element R. When the number of atoms of Cu existing in an R-rich phase contained in a grain boundary triple point 6 of the crystal particle 4 positioned on a surface part 40 of the rare earth magnet 100 is [Cu], the number of atoms of Fe existing in the R-rich phase is [Fe], and the number of atoms of R existing in the R-rich phase is [R], [Cu]>[Fe], and [Cu]/[R]>0.5.

Description

本発明は、希土類磁石及び回転機に関する。   The present invention relates to a rare earth magnet and a rotating machine.

希土類元素Ｒ、鉄元素（Ｆｅ）又はコバルト元素（Ｃｏ）等の遷移金属元素Ｔ及びホウ素元素Ｂを含有するＲ−Ｔ−Ｂ系希土類磁石は優れた磁気特性を有する（下記特許文献１参照）。しかし、希土類磁石は主成分として酸化され易い希土類元素を含有していることから耐食性が低い傾向にある。そのため、希土類磁石の耐食性を向上させるために、磁石素体の表面上に樹脂やめっき等からなる保護層を設けることが多い。   An RTB-based rare earth magnet containing a transition metal element T such as a rare earth element R, an iron element (Fe), or a cobalt element (Co) and a boron element B has excellent magnetic properties (see Patent Document 1 below). . However, since the rare earth magnet contains a rare earth element that is easily oxidized as a main component, the corrosion resistance tends to be low. Therefore, in order to improve the corrosion resistance of the rare earth magnet, a protective layer made of resin, plating or the like is often provided on the surface of the magnet body.

国際公開第２００６／１１２４０３号パンフレットInternational Publication No. 2006/112403 Pamphlet

しかし、表面に保護層を形成した希土類磁石においても、必ずしも完全な耐食性は得られていない。これは、高温多湿の環境では水蒸気が保護層を透過して磁石素体に到達することにより、磁石素体の腐食が進行することによる。   However, even a rare-earth magnet having a protective layer formed on its surface does not necessarily have complete corrosion resistance. This is because, in a high temperature and high humidity environment, the water vapor permeates the protective layer and reaches the magnet body, thereby causing corrosion of the magnet body.

本発明は、このような従来技術の有する課題に鑑みてなされたものであり、耐食性に優れた希土類磁石を提供することを目的とする。また、本発明は、長期間に亘って優れた性能を維持することが可能な回転機を提供することを目的とする。   The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a rare earth magnet having excellent corrosion resistance. Moreover, an object of this invention is to provide the rotary machine which can maintain the outstanding performance over a long period of time.

本発明者らは、水蒸気による磁石素体の腐食メカニズムについて研究した結果、腐食反応で発生する水素が磁石素体中の粒界に存在するＲリッチ相に吸蔵されることにより、Ｒリッチ相の水酸化物への変化が加速され、それに伴う体積膨張による主相粒子の脱落によって、腐食が加速度的に磁石内部に進行していくことを発見した。なお、Ｒリッチ相とは、相を構成する元素の中で最も濃度（原子数の比率）が高い元素が希土類元素Ｒである相を意味する。Ｒは例えばＮｄである。   As a result of studying the corrosion mechanism of the magnet body due to water vapor, the present inventors have found that the hydrogen generated by the corrosion reaction is occluded by the R-rich phase existing at the grain boundary in the magnet body, thereby It was discovered that the corrosion progresses rapidly inside the magnet due to the acceleration of the change to hydroxide and the accompanying drop-out of the main phase particles due to volume expansion. The R-rich phase means a phase in which the element having the highest concentration (ratio of the number of atoms) among the elements constituting the phase is the rare earth element R. R is, for example, Nd.

そこで本発明者らは、粒界のＲリッチ相による水素の吸蔵を抑制する方法について鋭意研究し、磁石素体の表面近傍のＲリッチ相内にＣｕを拡散させることにより、水素吸蔵を抑制し、耐食性を大幅に向上できることを見出し、下記の本発明に至った。   Therefore, the present inventors have intensively studied a method of suppressing hydrogen occlusion by the R-rich phase at the grain boundary, and suppressing hydrogen occlusion by diffusing Cu into the R-rich phase near the surface of the magnet body. The inventors have found that the corrosion resistance can be greatly improved, and have reached the following present invention.

本発明の希土類磁石は、希土類元素Ｒを含むＲ−Ｆｅ−Ｂ系合金の結晶粒子群を備える希土類磁石であって、希土類磁石の表面部に位置する結晶粒子の粒界三重点に含まれるＲリッチ相に存在するＣｕの原子数が[Ｃｕ]であり、当該Ｒリッチ相に存在するＦｅの原子数が[Ｆｅ]であり、当該Ｒリッチ相に存在するＲの原子数が[Ｒ]であるとき、[Ｃｕ]＞[Ｆｅ]であり、[Ｃｕ]／[Ｒ]＞０．５である。なお、結晶粒子群とは、複数の結晶粒子を意味する。   The rare earth magnet of the present invention is a rare earth magnet including a crystal particle group of an R—Fe—B alloy containing a rare earth element R, and is included in a grain boundary triple point of crystal grains located on the surface portion of the rare earth magnet. The number of Cu atoms present in the rich phase is [Cu], the number of Fe atoms present in the R rich phase is [Fe], and the number of R atoms present in the R rich phase is [R]. At some point, [Cu]> [Fe] and [Cu] / [R]> 0.5. The crystal particle group means a plurality of crystal particles.

上記本発明によれば、希土類磁石の粒界相による水素の吸蔵が抑制され、希土類磁石の耐食性が向上する。   According to the present invention, the occlusion of hydrogen by the grain boundary phase of the rare earth magnet is suppressed, and the corrosion resistance of the rare earth magnet is improved.

上記本発明では、結晶粒子におけるＣｕの含有率が０．０５原子％以下であることが好ましい。これにより、耐食性のみならず充分な磁気特性が希土類磁石に付与される。   In the said invention, it is preferable that the content rate of Cu in a crystal grain is 0.05 atomic% or less. Thereby, not only corrosion resistance but sufficient magnetic properties are imparted to the rare earth magnet.

上記本発明では、希土類磁石全体に占める結晶粒子群の割合が８５体積％以上であることが好ましい。これにより、耐食性のみならず充分な磁気特性が希土類磁石に付与される。   In the said invention, it is preferable that the ratio of the crystal grain group to the whole rare earth magnet is 85 volume% or more. Thereby, not only corrosion resistance but sufficient magnetic properties are imparted to the rare earth magnet.

本発明の回転機は、上記本発明の希土類磁石を備える。耐食性に優れた希土類磁石を備える回転機は、苛酷な環境下で使用しても、長期間に亘って優れた性能を維持することができる。   The rotating machine of the present invention includes the rare earth magnet of the present invention. A rotating machine including a rare earth magnet having excellent corrosion resistance can maintain excellent performance for a long period of time even when used in a harsh environment.

本発明によれば、耐食性に優れた希土類磁石を提供することが可能となる。また、本発明によれば、長期間に亘って優れた性能を維持することが可能な回転機を提供することが可能となる。   According to the present invention, it is possible to provide a rare earth magnet having excellent corrosion resistance. Moreover, according to this invention, it becomes possible to provide the rotary machine which can maintain the outstanding performance over a long period of time.

図１は、本発明の一実施形態に係る希土類磁石の斜視図である。FIG. 1 is a perspective view of a rare earth magnet according to an embodiment of the present invention. 図１に示す希土類磁石のＩＩ−ＩＩ線断面図である。It is the II-II sectional view taken on the line of the rare earth magnet shown in FIG. 図２に示す希土類磁石の表面部４０の一部を拡大した模式図である。It is the schematic diagram which expanded a part of surface part 40 of the rare earth magnet shown in FIG. 図４は、本発明の一実施形態に係る回転機を模式的に示す斜視図である。FIG. 4 is a perspective view schematically showing a rotating machine according to an embodiment of the present invention. 図５は、電子線マイクロアナライザー（Ｅｌｅｃｔｒｏｎ Ｐｒｏｂｅ Ｍｉｃｒｏ Ａｎａｌｙｚｅｒ：ＥＰＭＡ）による分析に基づいて作成した実施例１の希土類磁石の表面部におけるＣｕの分布図である。FIG. 5 is a distribution diagram of Cu in the surface portion of the rare earth magnet of Example 1 created based on an analysis by an electron probe microanalyzer (EPMA).

以下、図面を参照しながら、本発明の好適な一実施形態について詳細に説明する。ただし、本発明は下記の実施形態に限定されるものではない。なお、図面において、同一の要素については同一の符号を付し、同一の要素の符号の一部は省略する。   Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. In the drawings, the same elements are denoted by the same reference numerals, and some of the reference numerals of the same elements are omitted.

（希土類磁石）
図１〜３に示すように、本実施形態の希土類磁石１００は、複数の結晶粒子４（主相粒子）を備える。希土類磁石１００の主相は結晶粒子４から構成される。結晶粒子４は、主成分としてＲ−Ｆｅ−Ｂ系合金を含む。Ｒ−Ｆｅ−Ｂ系合金とは、例えばＲ２Ｆｅ１４Ｂ系合金等である。希土類磁石１００は複数の結晶粒子４の間に位置する粒界相を備える。粒界相はＲリッチ相、Ｂリッチ相、酸化物相及び炭化物相などから構成される。Ｂリッチ相とは、相中のＢ元素量が結晶粒子４中に含まれる量よりも多い相である。酸化物相とは、相を構成する元素の中で酸素元素が元素比で２０％以上含まれる相である。炭化物相とは、相を構成する元素の中で炭素元素が元素比で２０％以上含まれる相である。 (Rare earth magnet)
As shown in FIGS. 1 to 3, the rare earth magnet 100 of the present embodiment includes a plurality of crystal particles 4 (main phase particles). The main phase of the rare earth magnet 100 is composed of crystal particles 4. The crystal particles 4 contain an R—Fe—B alloy as a main component. The R—Fe—B alloy is, for example, an R 2 Fe 14 B alloy. The rare earth magnet 100 includes a grain boundary phase located between the plurality of crystal grains 4. The grain boundary phase is composed of an R-rich phase, a B-rich phase, an oxide phase, a carbide phase, and the like. The B-rich phase is a phase in which the amount of B element in the phase is larger than the amount contained in the crystal particles 4. The oxide phase is a phase in which an oxygen element is contained in an element ratio of 20% or more among elements constituting the phase. The carbide phase is a phase in which carbon elements are contained in an element ratio of 20% or more among elements constituting the phase.

希土類磁石１００の寸法は、特に限定されないが、縦の長さが１〜２００ｍｍ、横の長さが１〜２００ｍｍ、高さが１〜３０ｍｍ程度である。結晶粒子４の平均粒径は、特に限定されないが、１〜２０μｍ程度である。なお、希土類磁石１００の形状は、特に限定されず、リング状や円板状であってもよい。   The dimensions of the rare earth magnet 100 are not particularly limited, but the vertical length is 1 to 200 mm, the horizontal length is 1 to 200 mm, and the height is about 1 to 30 mm. The average particle size of the crystal particles 4 is not particularly limited, but is about 1 to 20 μm. The shape of the rare earth magnet 100 is not particularly limited, and may be a ring shape or a disk shape.

希土類元素Ｒは、Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｐｍ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ及びＬｕからなる群より選ばれる少なくとも一種であればよい。特に、希土類元素ＲがＮｄ及びＰｒのうち少なくともいずれか一種であることが好ましい。これにより、希土類磁石１００の飽和磁束密度及び保磁力が顕著に向上する。   The rare earth element R may be at least one selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. In particular, the rare earth element R is preferably at least one of Nd and Pr. Thereby, the saturation magnetic flux density and the coercive force of the rare earth magnet 100 are remarkably improved.

希土類磁石１００の主相及び粒界相は、必要に応じてＣｏ、Ｃｕ、Ｎｉ、Ｍｎ、Ａｌ、Ｎｂ、Ｚｒ、Ｔｉ、Ｗ、Ｍｏ、Ｖ、Ｇａ、Ｚｎ、Ｓｉ及びＢｉ等の他の元素を更に含んでもよい。   The main phase and the grain boundary phase of the rare earth magnet 100 may include other elements such as Co, Cu, Ni, Mn, Al, Nb, Zr, Ti, W, Mo, V, Ga, Zn, Si, and Bi as necessary. May further be included.

希土類磁石１００の表面部４０に位置する粒界三重点６に含まれるＲリッチ相には、Ｃｕが偏析している。換言すれば、希土類磁石１００の表面部４０に位置する粒界三重点６におけるＣｕの含有率は、主相（結晶粒子群）と比較して著しく高い。なお、粒界三重点６とは３つ以上の結晶粒子４に囲まれた粒界相を意味する。希土類磁石１００の表面部４０に位置する粒界三重点６に含まれるＲリッチ相に存在するＣｕの原子数が[Ｃｕ]であり、粒界三重点６に含まれるＲリッチ相に存在するＦｅの原子数が[Ｆｅ]であり、粒界三重点６に含まれるＲリッチ相に存在するＲの原子数が[Ｒ]であるとき、[Ｃｕ]＞[Ｆｅ]であり、[Ｃｕ]／[Ｒ]＞０．５である。以下では、[Ｃｕ]＞[Ｆｅ]であり、且つ[Ｃｕ]／[Ｒ]＞０．５であり、粒界三重点６に含まれるＲリッチ相を、場合により「Ｒ−Ｃｕリッチ相」と記す。なお、Ｒ−Ｃｕリッチ相では、[Ｃｕ]／[Ｒ]≦１である。   Cu is segregated in the R-rich phase contained in the grain boundary triple point 6 located on the surface portion 40 of the rare earth magnet 100. In other words, the Cu content at the grain boundary triple point 6 located on the surface portion 40 of the rare earth magnet 100 is significantly higher than that of the main phase (crystal grain group). The grain boundary triple point 6 means a grain boundary phase surrounded by three or more crystal grains 4. The number of Cu atoms present in the R-rich phase contained in the grain boundary triple point 6 located on the surface portion 40 of the rare earth magnet 100 is [Cu], and Fe present in the R-rich phase contained in the grain boundary triple point 6. Is [Fe], and when the number of R atoms present in the R-rich phase contained in the grain boundary triple point 6 is [R], [Cu]> [Fe], and [Cu] / [R]> 0.5. In the following, [Cu]> [Fe] and [Cu] / [R]> 0.5, and the R-rich phase contained in the grain boundary triple point 6 is sometimes referred to as “R-Cu-rich phase”. . In the R-Cu rich phase, [Cu] / [R] ≦ 1.

Ｒ−Ｃｕリッチ相は、水素を吸蔵し難い特性を有する。したがって、仮に水蒸気によって希土類磁石の表面が腐食して水素が発生した場合であっても、希土類磁石１００の表面部４０に位置するＲ−Ｃｕリッチ相によって、希土類磁石内部のＲリッチ相への水素の侵入及び吸蔵が抑制される。その結果、水素とＲリッチ相との反応が抑制され、腐食が希土類磁石の表面から内部へ進行し難くなる。   The R-Cu rich phase has a characteristic that it is difficult to occlude hydrogen. Therefore, even if the surface of the rare earth magnet is corroded by water vapor and hydrogen is generated, the R-Cu rich phase located on the surface portion 40 of the rare earth magnet 100 causes hydrogen to enter the R rich phase inside the rare earth magnet. Intrusion and occlusion are suppressed. As a result, the reaction between hydrogen and the R-rich phase is suppressed, and corrosion hardly proceeds from the surface of the rare earth magnet to the inside.

希土類磁石１００に適量のＣｕが含まれると、希土類磁石１００の保磁力が向上する。しかし、過度のＣｕが希土類磁石１００の全域に含まれると希土類磁石１００の保磁力は低下する傾向がある。したがって、Ｒ−Ｃｕリッチ相は希土類磁石１００の表面部４０だけに偏在することが好ましい。これにより、希土類磁石１００の保磁力及び飽和磁束密度を損なうことなく希土類磁石１００の耐食性を向上させ易くなる。なお、深さＤは、表面部４０の厚さに相当する。充分な耐食性と磁気特性を両立させるためには、表面部４０の厚さＤは４０μｍ以上であることが好ましく、３００μｍ以上であることがより好ましい。   When the rare earth magnet 100 contains an appropriate amount of Cu, the coercive force of the rare earth magnet 100 is improved. However, when excessive Cu is contained in the entire area of the rare earth magnet 100, the coercive force of the rare earth magnet 100 tends to decrease. Therefore, it is preferable that the R—Cu rich phase is unevenly distributed only on the surface portion 40 of the rare earth magnet 100. Thereby, it becomes easy to improve the corrosion resistance of the rare earth magnet 100 without impairing the coercive force and the saturation magnetic flux density of the rare earth magnet 100. The depth D corresponds to the thickness of the surface portion 40. In order to achieve both sufficient corrosion resistance and magnetic properties, the thickness D of the surface portion 40 is preferably 40 μm or more, and more preferably 300 μm or more.

希土類磁石１００の表面部４０におけるＣｏの含有率（原子数の比率）は、希土類磁石１００の中心部におけるＣｏの含有率よりも高いことが好ましい。この場合、希土類磁石１００の耐食性が向上し易い傾向がある。   The Co content (ratio of the number of atoms) in the surface portion 40 of the rare earth magnet 100 is preferably higher than the Co content in the central portion of the rare earth magnet 100. In this case, the corrosion resistance of the rare earth magnet 100 tends to be improved.

結晶粒子４におけるＣｕの含有率は０．０５原子％以下であることが好ましい。換言すれば、希土類磁石１００の主相におけるＣｕの含有率は０．０５原子％以下であることが好ましい。主相におけるＣｕの含有率が高過ぎる場合、希土類磁石１００の飽和磁束密度が低下する傾向があるが、Ｃｕの含有率を上記の上限値以下とすることにより、希土類磁石１００の磁気特性の劣化を抑制できる。ただし、Ｃｕの含有率が上記の上限値を超えたとしても、本発明の効果は達成される。   The content of Cu in the crystal particles 4 is preferably 0.05 atomic% or less. In other words, the Cu content in the main phase of the rare earth magnet 100 is preferably 0.05 atomic% or less. When the Cu content in the main phase is too high, the saturation magnetic flux density of the rare earth magnet 100 tends to decrease. Can be suppressed. However, even if the Cu content exceeds the upper limit, the effect of the present invention is achieved.

結晶粒子４からなる主相の割合は希土類磁石１００全体に対して８５体積％以上であることが好ましい。これにより、充分な磁気特性が希土類磁石に付与される。   The proportion of the main phase composed of the crystal particles 4 is preferably 85% by volume or more with respect to the entire rare earth magnet 100. Thereby, sufficient magnetic properties are imparted to the rare earth magnet.

表面部４０に存在するＲ−Ｃｕリッチ相中のＣｏの原子数を[Ｃｏ]とするとき、［Ｃｕ］＞［Ｃｏ］＞０であることが好ましい。また、Ｒ−Ｃｕリッチ相全体に対するＣｏの含有率は、０．５原子％超１１原子％未満であることが好ましく、１原子％以上４原子％以下であることがより好ましい。Ｒ−Ｃｕリッチ相においてＣｕとＣｏが共存し、Ｃｏが上記の条件を満たすことにより、希土類磁石の耐食性が顕著に向上する。   When the number of Co atoms in the R—Cu rich phase present on the surface portion 40 is [Co], it is preferable that [Cu]> [Co]> 0. Further, the Co content with respect to the entire R-Cu rich phase is preferably more than 0.5 atom% and less than 11 atom%, and more preferably 1 atom% or more and 4 atom% or less. In the R-Cu rich phase, Cu and Co coexist and Co satisfies the above conditions, thereby significantly improving the corrosion resistance of the rare earth magnet.

希土類磁石１００は、必要に応じてさらにその表面に保護層を備えてもよい。保護層としては、通常希土類磁石の表面を保護する層として形成されるものであれば特に制限なく適用できる。保護層としては、たとえば、塗装や蒸着重合法により形成した樹脂層、めっきや気相法により形成した金属層、塗布法や気相法により形成した無機層、酸化層、化成処理層等が挙げられる。   The rare earth magnet 100 may further include a protective layer on the surface thereof as necessary. Any protective layer can be used without particular limitation as long as it is usually formed as a layer that protects the surface of the rare earth magnet. Examples of the protective layer include a resin layer formed by painting or vapor deposition polymerization method, a metal layer formed by plating or vapor phase method, an inorganic layer formed by coating method or vapor phase method, an oxide layer, a chemical conversion treatment layer, and the like. It is done.

（希土類磁石の製造方法）
希土類磁石の製造では、まず原料合金を鋳造し、インゴットを得る。原料合金としては、希土類元素Ｒ，Ｆｅ及びＢを含むものを用いればよい。原料合金は、必要に応じてＣｏ、Ｃｕ、Ｎｉ、Ｍｎ、Ａｌ、Ｎｂ、Ｚｒ、Ｔｉ、Ｗ、Ｍｏ、Ｖ、Ｇａ、Ｚｎ、Ｓｉ及びＢｉ等の元素を更に含んでもよい。インゴットの化学組成は、最終的に得たい希土類磁石の主相及び粒界相の化学組成に応じて調整すればよい。 (Rare earth magnet manufacturing method)
In the production of rare earth magnets, a raw material alloy is first cast to obtain an ingot. As the raw material alloy, an alloy containing rare earth elements R, Fe and B may be used. The raw material alloy may further contain elements such as Co, Cu, Ni, Mn, Al, Nb, Zr, Ti, W, Mo, V, Ga, Zn, Si, and Bi as necessary. The chemical composition of the ingot may be adjusted according to the chemical composition of the main phase and the grain boundary phase of the rare earth magnet to be finally obtained.

インゴットを、ディスクミル等により粗粉砕して１０〜１００μｍ程度の粒径の合金粉末を得る。当該合金粉末を、ジェットミル等により微粉砕して０．５〜５μｍ程度の粒径の合金粉末を得る。当該合金粉末を、磁場中で加圧成形する。成形時に合金粉末に印加する磁場の強度は８００ｋＡ／ｍ以上であることが好ましい。成形時に合金粉末に加える圧力は１０〜５００ＭＰａ程度であることが好ましい。成形方法としては、一軸加圧法またはＣＩＰなどの等方加圧法のいずれを用いてもよい。得られた成形体を焼成して焼結体を形成する。焼成温度は１０００〜１２００℃程度であればよい。焼成時間は０．１〜１００時間程度であればよい。焼成工程は、複数回行ってもよい。焼成工程は、真空中またはＡｒガス等の不活性ガス雰囲気中で行うことが好ましい。   The ingot is roughly pulverized by a disk mill or the like to obtain an alloy powder having a particle size of about 10 to 100 μm. The alloy powder is pulverized by a jet mill or the like to obtain an alloy powder having a particle size of about 0.5 to 5 μm. The alloy powder is pressure-molded in a magnetic field. The strength of the magnetic field applied to the alloy powder during molding is preferably 800 kA / m or more. The pressure applied to the alloy powder during molding is preferably about 10 to 500 MPa. As the molding method, either a uniaxial pressing method or an isotropic pressing method such as CIP may be used. The obtained molded body is fired to form a sintered body. The baking temperature should just be about 1000-1200 degreeC. The firing time may be about 0.1 to 100 hours. You may perform a baking process in multiple times. The firing step is preferably performed in a vacuum or in an inert gas atmosphere such as Ar gas.

焼結体に対して時効処理を施すことが好ましい。時効処理では、焼結体を４５０〜９５０℃程度で熱処理すればよい。時効処理では、焼結体を０．１〜１００時間程度熱処理すればよい。時効処理は不活性ガス雰囲気中で行えばよい。このような時効処理により希土類磁石の保磁力がさらに向上する。なお、時効処理は多段階の熱処理工程から構成されてもよい。例えば２段の熱処理からなる時効処理では、１段目の熱処理工程で焼結体を７００℃以上焼成温度未満の温度で０．１〜５０時間加熱すればよい。２段目の熱処理工程では、焼結体を４５０〜７００℃で０．１〜１００時間加熱すればよい。   It is preferable to apply an aging treatment to the sintered body. In the aging treatment, the sintered body may be heat-treated at about 450 to 950 ° C. In the aging treatment, the sintered body may be heat treated for about 0.1 to 100 hours. The aging treatment may be performed in an inert gas atmosphere. Such an aging treatment further improves the coercivity of the rare earth magnet. The aging treatment may be composed of a multi-step heat treatment process. For example, in the aging treatment comprising two stages of heat treatment, the sintered body may be heated at a temperature of 700 ° C. or higher and lower than the firing temperature for 0.1 to 50 hours in the first stage heat treatment step. In the second heat treatment step, the sintered body may be heated at 450 to 700 ° C. for 0.1 to 100 hours.

以上の工程により得られた焼結体は、Ｒ−Ｆｅ−Ｂ系合金の結晶粒子群４からなる主相と、希土類元素Ｒを主成分とするＲリッチ相を少なくとも備える。   The sintered body obtained by the above process includes at least a main phase composed of the crystal particle group 4 of the R—Fe—B based alloy and an R rich phase containing the rare earth element R as a main component.

焼結体から所望の寸法の磁石素体を切り出し、磁石素体の表面にＣｕ単体、Ｃｕ合金、又はＣｕ化合物を付着させる。Ｃｕの付着方法としては、例えば、Ｃｕからなる粒子を分散させた塗布液を、磁石素体の表面全体に均一に塗布する方法が挙げられる。磁石素体の表面に付着させるＣｕ粒子の粒径は、５０μｍ以下であることが好ましい。Ｃｕ粒子の粒径が大き過ぎる場合、Ｃｕが磁石素体内へ拡散しにくくなることが問題となる。なお、めっき法や気相法などの手法により、磁石素体の表面にＣｕを付着させてもよい。   A magnet body having a desired size is cut out from the sintered body, and Cu alone, a Cu alloy, or a Cu compound is attached to the surface of the magnet body. Examples of the Cu adhesion method include a method in which a coating liquid in which particles made of Cu are dispersed is uniformly applied to the entire surface of the magnet body. The particle size of the Cu particles to be attached to the surface of the magnet body is preferably 50 μm or less. When the particle size of the Cu particles is too large, it becomes a problem that Cu is difficult to diffuse into the magnet body. Note that Cu may be attached to the surface of the magnet body by a technique such as plating or vapor phase.

表面にＣｕを付着させた磁石素体を熱処理する。これにより、Ｃｕが磁石素体の表面から磁石素体のＲリッチ相へ熱拡散して、表面部４０のＲリッチ相がＲ−Ｃｕリッチ相になり、本実施形態の希土類磁石が完成する。表面にＣｕを付着させた磁石素体は６５０℃以下で熱処理することが好ましく、６００℃以下で熱処理することがより好ましい。これにより、Ｒ−Ｃｕリッチ相を希土類磁石の表面部だけに形成し易くなる。表面にＣｕを付着させた磁石素体の熱処理温度が高過ぎる場合、Ｃｕが磁石素体の表面部の粒界三重点に含まれるＲリッチ相のみならず磁石素体の全体に熱拡散したり、Ｃｕが溶融して磁石素体の主相（Ｒ−Ｆｅ−Ｂ系合金）と反応して合金化したりする。その結果、希土類磁石の磁気特性が劣化する。   A magnet body with Cu deposited on the surface is heat-treated. Thereby, Cu is thermally diffused from the surface of the magnet body to the R-rich phase of the magnet body, and the R-rich phase of the surface portion 40 becomes the R-Cu-rich phase, thereby completing the rare earth magnet of the present embodiment. The magnet body with Cu attached to the surface is preferably heat-treated at 650 ° C. or less, more preferably at 600 ° C. or less. Thereby, it becomes easy to form the R-Cu rich phase only on the surface portion of the rare earth magnet. When the heat treatment temperature of the magnet body with Cu attached to the surface is too high, Cu diffuses not only to the R-rich phase contained in the grain boundary triple point on the surface of the magnet body but also to the entire magnet body. Cu melts and reacts with the main phase (R—Fe—B alloy) of the magnet body to form an alloy. As a result, the magnetic properties of the rare earth magnet deteriorate.

上記の熱処理において昇温させた磁石素体を、３０℃／分以上の冷却速度で急冷することが好ましい。これにより、Ｒ−Ｃｕリッチ相を希土類磁石の表面部だけに形成し易くなる。   It is preferable that the magnet body heated in the heat treatment is rapidly cooled at a cooling rate of 30 ° C./min or more. Thereby, it becomes easy to form the R-Cu rich phase only on the surface portion of the rare earth magnet.

磁石素体表面からのＣｕの拡散距離Ｄ、表面部のＲ−Ｃｕリッチ相における[Ｃｕ]，[Ｆｅ]及び[Ｒ]、並びに希土類磁石全体に対する主相の割合は、原料合金の組成、磁石素体の表面に付着させるＣｕの量、表面にＣｕを付着させた磁石素体の熱処理温度又は熱処理時間等によって適宜制御できる。   The diffusion distance D of Cu from the surface of the magnet body, [Cu], [Fe] and [R] in the R-Cu rich phase on the surface, and the ratio of the main phase to the entire rare earth magnet are the composition of the raw material alloy, magnet It can be appropriately controlled depending on the amount of Cu to be adhered to the surface of the element body, the heat treatment temperature or the heat treatment time of the magnet element body on which Cu is adhered to the surface.

希土類磁石に対して、上述した焼結体の場合と同様の時効処理を施すことが好ましい。時効処理により希土類磁石の保磁力がさらに向上する。時効処理温度は、Ｃｕの熱拡散に要する熱処理温度以下であることが好ましい。時効処理において昇温させた希土類磁石を、３０℃／分以上の冷却速度で急冷することが好ましい。これにより、希土類磁石の磁気特性が向上し易くなる。   It is preferable to apply the same aging treatment to the rare earth magnet as in the case of the sintered body described above. The coercive force of the rare earth magnet is further improved by the aging treatment. The aging treatment temperature is preferably equal to or lower than the heat treatment temperature required for thermal diffusion of Cu. It is preferable to rapidly cool the rare earth magnet heated in the aging treatment at a cooling rate of 30 ° C./min or more. Thereby, the magnetic characteristics of the rare earth magnet are easily improved.

表面にＣｕを付着させた磁石素体を熱処理した後、希土類磁石の表面に残存するＣｕ等を研磨やエッチングにより除去してもよい。希土類磁石の表面に保護層を形成してもよい。保護層としては、通常希土類磁石の表面を保護する層として形成されるものであれば特に制限なく適用できる。保護層としては、たとえば、塗装や蒸着重合法により形成した樹脂層、めっきや気相法により形成した金属層、塗布法や気相法により形成した無機層、酸化層、化成処理層等が挙げられる。   After heat-treating the magnet body with Cu attached to the surface, Cu remaining on the surface of the rare earth magnet may be removed by polishing or etching. A protective layer may be formed on the surface of the rare earth magnet. Any protective layer can be used without particular limitation as long as it is usually formed as a layer that protects the surface of the rare earth magnet. Examples of the protective layer include a resin layer formed by painting or vapor deposition polymerization method, a metal layer formed by plating or vapor phase method, an inorganic layer formed by coating method or vapor phase method, an oxide layer, a chemical conversion treatment layer, and the like. It is done.

（回転機）
図４は、本実施形態の回転機（永久磁石回転機）の内部構造を示す説明図である。本実施形態の回転機２００は、永久磁石同期回転機（ＳＰＭ回転機）であり、円筒状のロータ５０と該ロータ５０の内側に配置されるステータ３０とを備えている。ロータ５０は、円筒状のコア５２と円筒状のコア５２の内周面に沿ってＮ極とＳ極が交互になるように複数の希土類磁石１００が設けられている。ステータ３０は、内周面に沿って設けられた複数のコイル３２を有している。このコイル３２と希土類磁石１００とは互いに対向するように配置されている。 (Rotating machine)
FIG. 4 is an explanatory diagram showing the internal structure of the rotating machine (permanent magnet rotating machine) of the present embodiment. The rotating machine 200 of this embodiment is a permanent magnet synchronous rotating machine (SPM rotating machine), and includes a cylindrical rotor 50 and a stator 30 disposed inside the rotor 50. The rotor 50 is provided with a plurality of rare earth magnets 100 so that N poles and S poles are alternated along the inner circumferential surface of the cylindrical core 52 and the cylindrical core 52. The stator 30 has a plurality of coils 32 provided along the inner peripheral surface. The coil 32 and the rare earth magnet 100 are arranged to face each other.

回転機２００は、ロータ５０に、上記実施形態に係る希土類磁石１００を備える。希土類磁石１００は耐食性に優れるため、経時的な磁気特性の低下を十分に抑制することができる。したがって、回転機２００は優れた性能を長時間にわたって維持することができる。回転機２００は、希土類磁石１００以外の部分について、通常の回転機部品を用いて通常の方法によって製造することができる。   The rotating machine 200 includes the rare earth magnet 100 according to the above embodiment in the rotor 50. Since the rare earth magnet 100 is excellent in corrosion resistance, it is possible to sufficiently suppress a decrease in magnetic characteristics over time. Therefore, the rotating machine 200 can maintain excellent performance for a long time. The rotating machine 200 can be manufactured by a normal method using normal rotating machine parts for parts other than the rare earth magnet 100.

回転機２００は、コイル３２に通電することによって生成する電磁石による界磁と永久磁石１００による界磁との相互作用により、電気エネルギーを機械的エネルギーに変換する電動機（モータ）であってもよい。また、回転機２００は、永久磁石１００による界磁とコイル３２との電磁誘導相互作用により、機械的エネルギーから電気的エネルギーに変換する発電機（ジェネレータ）であってもよい。   The rotating machine 200 may be an electric motor (motor) that converts electrical energy into mechanical energy by the interaction between the field by the electromagnet generated by energizing the coil 32 and the field by the permanent magnet 100. Further, the rotating machine 200 may be a generator that converts mechanical energy into electrical energy by electromagnetic induction interaction between the field by the permanent magnet 100 and the coil 32.

電動機（モータ）として機能する回転機２００としては、例えば、永久磁石直流モータ、リニア同期モータ、永久磁石同期モータ（ＳＰＭモータ）、永久磁石同期モータ（ＩＰＭモータ）、往復動モータなどが挙げられる。往復動モータとして機能するモータとしては、例えば、ボイスコイルモータ、振動モータなどが挙げられる。発電機（ジェネレータ）として機能する回転機２００としては、例えば、永久磁石同期発電機、永久磁石整流子発電機、永久磁石交流発電機などが挙げられる。   Examples of the rotating machine 200 that functions as an electric motor (motor) include a permanent magnet DC motor, a linear synchronous motor, a permanent magnet synchronous motor (SPM motor), a permanent magnet synchronous motor (IPM motor), and a reciprocating motor. Examples of the motor that functions as a reciprocating motor include a voice coil motor and a vibration motor. Examples of the rotating machine 200 that functions as a generator include a permanent magnet synchronous generator, a permanent magnet commutator generator, and a permanent magnet AC generator.

以下、本発明を実施例により更に詳細に説明するが、本発明はこれらの実施例に限定されるものではない。   EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.

（実施例１）
粉末冶金法により、組成が２２．５重量％Ｎｄ−５．２重量％Ｐｒ−２．７重量％Ｄｙ−０．５重量％Ｃｏ−０．３重量％Ａｌ−０．０７重量％Ｃｕ−１．０重量％Ｂ−残部Ｆｅである鋳塊を作製した。鋳塊を粗粉砕して得た粗粉末を不活性ガス中でジェットミルにより粉砕して、平均粒径が約３．５μｍの微粉末を得た。微粉末を金型内に充填し、磁場中で加圧成形して成形体を得た。成形体を真空中で焼成した後、時効処理を施して焼結体を得た。焼結体を切り出し加工し、１０ｍｍ×８ｍｍ×１２ｍｍの寸法を有する磁石素体を作製した。 Example 1
According to the powder metallurgy method, the composition is 22.5 wt% Nd-5.2 wt% Pr-2.7 wt% Dy-0.5 wt% Co-0.3 wt% Al-0.07 wt% Cu-1 An ingot with 0.0 wt% B-balance Fe was prepared. The coarse powder obtained by coarsely pulverizing the ingot was pulverized by a jet mill in an inert gas to obtain a fine powder having an average particle diameter of about 3.5 μm. The fine powder was filled into a mold and pressure molded in a magnetic field to obtain a molded body. After the molded body was fired in vacuum, an aging treatment was performed to obtain a sintered body. The sintered body was cut out and processed to produce a magnet body having a size of 10 mm × 8 mm × 12 mm.

磁石素体の表面に対して脱脂処理及びエッチングを施した。平均粒径１μｍのＣｕ粒子を分散させた塗布液を調製した。エッチング後の磁石素体の表面に塗布液をディップコーティングにより塗布し、厚さが約３μｍの塗膜を磁石素体の表面全体に形成した。この塗膜を１２０℃で２０分乾燥させた。   The surface of the magnet body was degreased and etched. A coating solution in which Cu particles having an average particle diameter of 1 μm were dispersed was prepared. A coating solution was applied to the surface of the magnet body after etching by dip coating to form a coating film having a thickness of about 3 μm on the entire surface of the magnet body. This coating film was dried at 120 ° C. for 20 minutes.

塗膜を有する磁石素体をＡｒ雰囲気において６００℃で１時間熱処理した後、５０℃／分で急冷し、塗膜中のＣｕを磁石素体内へ拡散させた。熱処理後の磁石素体をＡｒ雰囲気において４７０℃で１時間時効処理した後、５０℃／分で急冷した。時効処理後の磁石素体の表面に残存した反応物を研磨で除去し、磁石素体の表面にエッチングを施すことで、実施例１の希土類磁石を得た。   The magnet body having a coating film was heat-treated at 600 ° C. for 1 hour in an Ar atmosphere, and then rapidly cooled at 50 ° C./min to diffuse Cu in the coating film into the magnet body. The magnet body after the heat treatment was aged at 470 ° C. for 1 hour in an Ar atmosphere, and then rapidly cooled at 50 ° C./min. The reaction product remaining on the surface of the magnet body after the aging treatment was removed by polishing, and the surface of the magnet body was etched to obtain the rare earth magnet of Example 1.

（実施例２）
実施例２では、実施例１と同様の方法で焼結体を作成した。焼結体を切り出し加工し、１０ｍｍ×８ｍｍ×１ｍｍの寸法を有する磁石素体を作製した。実施例２では、Ｃｕ粒子を分散させた塗布液を磁石素体の表面に塗布する代わりに、電気めっきにより厚さが１μｍのＣｕめっき膜を磁石素体の表面全体に形成した。Ｃｕめっき膜を有する磁石素体をＡｒ雰囲気中において６００℃で１０分間熱処理して、Ｃｕめっき膜中のＣｕを磁石素体内へ拡散させた。以上の事項以外は実施例１と同様の方法で実施例２の希土類磁石を作製した。 (Example 2)
In Example 2, a sintered body was prepared in the same manner as in Example 1. The sintered body was cut out and a magnet body having a size of 10 mm × 8 mm × 1 mm was produced. In Example 2, instead of applying the coating liquid in which Cu particles were dispersed to the surface of the magnet body, a Cu plating film having a thickness of 1 μm was formed on the entire surface of the magnet body by electroplating. The magnet body having the Cu plating film was heat-treated at 600 ° C. for 10 minutes in an Ar atmosphere to diffuse Cu in the Cu plating film into the magnet body. Except for the above, a rare earth magnet of Example 2 was produced in the same manner as in Example 1.

（実施例３）
実施例３では、Ｃｕめっき膜を有する磁石素体をＡｒ雰囲気において５５０℃で１０分熱処理した。この事項以外は実施例２と同様の方法で実施例３の希土類磁石を作製した。 (Example 3)
In Example 3, a magnet body having a Cu plating film was heat-treated at 550 ° C. for 10 minutes in an Ar atmosphere. Except for this, the rare earth magnet of Example 3 was produced in the same manner as in Example 2.

（実施例４）
実施例４では、Ｃｕめっき膜を有する磁石素体をＡｒ雰囲気において５００℃で１０分熱処理した。この事項以外は実施例２と同様の方法で実施例４の希土類磁石を作製した。 Example 4
In Example 4, a magnet body having a Cu plating film was heat-treated at 500 ° C. for 10 minutes in an Ar atmosphere. Except for this, the rare earth magnet of Example 4 was produced in the same manner as in Example 2.

（実施例５）
実施例５では、電気めっきにより磁石素体の表面に厚さが０．４μｍのＣｕめっき膜を形成した。Ｃｕめっき膜を有する磁石素体をＡｒ雰囲気において６００℃で６０分熱処理した。これらの事項以外は実施例２と同様の方法で実施例５の希土類磁石を作製した。 (Example 5)
In Example 5, a Cu plating film having a thickness of 0.4 μm was formed on the surface of the magnet body by electroplating. The magnet body having the Cu plating film was heat-treated at 600 ° C. for 60 minutes in an Ar atmosphere. Except for these matters, the rare earth magnet of Example 5 was produced in the same manner as in Example 2.

（比較例１）
磁石素体の表面のエッチング以降の工程を実施しなかったこと以外は実施例１と同様の方法で比較例１の希土類磁石を作製した。つまり、Ｃｕを用いずに比較例１の希土類磁石を作製した。 (Comparative Example 1)
A rare earth magnet of Comparative Example 1 was produced in the same manner as in Example 1 except that the steps after the etching of the surface of the magnet body were not performed. That is, the rare earth magnet of Comparative Example 1 was produced without using Cu.

（比較例２）
比較例２では、実施例１と同様のディップコーティングにより厚さが約１μｍの塗膜を磁石素体の表面全体に形成した。また、比較例２では、塗膜を有する磁石素体をＡｒ雰囲気において７００℃で１０分間熱処理した。これらの事項以外は実施例１と同様の方法で比較例２の希土類磁石を作製した。なお、比較例２の希土類磁石の保磁力は、後述するように、他の実施例及び比較例に対して著しく劣っていたので、比較例２の希土類磁石の組成の分析及び耐食性の評価は実施しなかった。比較例２の希土類磁石の保磁力の低下は、塗膜を有する磁石素体の熱処理温度が高過ぎたため、塗膜中のＣｕが粒界相のみならず主相全体に拡散してしまい、[Ｃｕ]＞[Ｆｅ]であり、[Ｃｕ]／[Ｒ]＞０．５であるＲ−Ｃｕリッチ相が表面部に形成されなかったことに起因する、と推測される。 (Comparative Example 2)
In Comparative Example 2, a coating film having a thickness of about 1 μm was formed on the entire surface of the magnet body by dip coating as in Example 1. In Comparative Example 2, the magnet body having a coating film was heat-treated at 700 ° C. for 10 minutes in an Ar atmosphere. Except for these matters, a rare earth magnet of Comparative Example 2 was produced in the same manner as in Example 1. In addition, since the coercive force of the rare earth magnet of Comparative Example 2 was significantly inferior to the other Examples and Comparative Examples, as will be described later, the analysis of the composition of the rare earth magnet of Comparative Example 2 and the evaluation of the corrosion resistance were performed. I did not. The decrease in the coercive force of the rare earth magnet of Comparative Example 2 is that the heat treatment temperature of the magnet body having the coating film was too high, so that Cu in the coating film diffused not only to the grain boundary phase but also to the entire main phase. It is presumed that Cu]> [Fe] and [Cu] / [R]> 0.5 resulting from the fact that the R—Cu rich phase was not formed on the surface portion.

［組成の分析］
実施例１〜５及び比較例１の各希土類磁石を切断し、研磨した切断面における元素分布をＥＰＭＡで確認した。ＥＰＭＡの装置としては、ＪＥＯＬ社製のＪＸＡ−８８００を用いた。ＥＰＭＡでは、希土類磁石の外表面からの深さが０〜１００μｍであり、外表面に平行な方向における幅が１００μｍである領域（以下、「表面部Ａ」という。）に存在する元素のマッピングを行い、Ｒリッチ相を特定してその相の直径１μｍのスポットの範囲を分析した。表面部Ａの面積は１００μｍ×１００μｍである。各希土類磁石の表面部Ａ中に存在する主相における各元素の含有率（原子％）及び［Ｃｕ]／[Ｒ]を表１に示す。各希土類磁石の表面部Ａ中に存在する粒界三重点に含まれるＲリッチ相における各元素の含有率（原子％）及び[Ｃｕ]／[Ｒ]を表１に示す。主相における各元素の含有率は、表面部Ａ内の任意の３つの主相粒子（結晶粒子）で測定した各元素の含有率の平均値である。粒界三重点に含まれるＲリッチ相における各元素の含有率は、表面部Ａ内の任意の３つの粒界三重点に含まれる各Ｒリッチ相で測定した各元素の含有率の平均値である。なお、各実施例の希土類磁石の主相の組成は同じであったため、表１には全実施例に共通する主相の組成を示す。また、実施例１の表面部ＡにおけるＣｕの分布図を図５に示す。図５の白い部分はＣｕが存在する部分である。 [Analysis of composition]
The rare earth magnets of Examples 1 to 5 and Comparative Example 1 were cut, and the element distribution on the polished cut surfaces was confirmed by EPMA. As an EPMA apparatus, JXA-8800 manufactured by JEOL was used. In EPMA, mapping of elements existing in a region (hereinafter referred to as “surface portion A”) in which the depth from the outer surface of the rare earth magnet is 0 to 100 μm and the width in the direction parallel to the outer surface is 100 μm. The R-rich phase was identified and the range of the 1 μm diameter spot of the phase was analyzed. The area of the surface portion A is 100 μm × 100 μm. Table 1 shows the content (atomic%) and [Cu] / [R] of each element in the main phase existing in the surface portion A of each rare earth magnet. Table 1 shows the content (atomic%) and [Cu] / [R] of each element in the R-rich phase contained in the grain boundary triple point existing in the surface portion A of each rare earth magnet. The content of each element in the main phase is an average value of the content of each element measured by any three main phase particles (crystal particles) in the surface portion A. The content of each element in the R-rich phase contained in the grain boundary triple point is the average value of the content of each element measured in each R-rich phase contained in any three grain boundary triple points in the surface portion A. is there. In addition, since the composition of the main phase of the rare earth magnet of each Example was the same, Table 1 shows the composition of the main phase common to all Examples. Moreover, the distribution map of Cu in the surface part A of Example 1 is shown in FIG. The white part of FIG. 5 is a part where Cu exists.

Figure 2011199183
Figure 2011199183

ＥＰＭＡによる分析の結果、実施例１〜５の各希土類磁石のいずれにおいても、Ｒ−Ｔ−Ｂ系合金の結晶粒子から構成される主相の比率は、希土類磁石全体に対して９２体積％であることが確認された。実施例１〜５の各希土類磁石の表面部では、比較例１と比較して粒界三重点に含まれるＲリッチ相に多量のＣｕが拡散していることが確認された。実施例１〜５の各粒界三重点のＣｕは主相内へ殆ど拡散していないことが確認された。実施例１〜５及び比較例１の粒界三重点に含まれるＲリッチ相のいずれにも、Ｃｕのほか少なくともＮｄ，Ｐｒ，Ｆｅ及びＣｏが存在していることが分かった。実施例１〜５及び比較例１の粒界三重点に含まれるＲリッチ相のいずれにも、Ｃｕと共にＣｏが偏在することが確認された。実施例１〜５及び比較例１の粒界三重点に含まれるＲリッチ相におけるＣｏの含有率は主相に比べて高いことが確認された。成形体を焼成して焼結体を形成する工程において、粒界相にＣｏが析出し、Ｃｕの拡散に誘起される形で磁石内部からＣｏが移動しＲ−Ｃｕリッチ相へ共析したものと推測される。また、ＥＰＭＡによる分析の結果、Ｃｕは、粒界三重点のＲリッチ相へ拡散し易い傾向があることが確認された。   As a result of analysis by EPMA, in each of the rare earth magnets of Examples 1 to 5, the ratio of the main phase composed of the crystal particles of the R—T—B system alloy was 92% by volume with respect to the whole rare earth magnet. It was confirmed that there was. In the surface portion of each rare earth magnet of Examples 1 to 5, it was confirmed that a large amount of Cu was diffused in the R-rich phase contained in the grain boundary triple point as compared with Comparative Example 1. It was confirmed that Cu at each grain boundary triple point of Examples 1 to 5 hardly diffused into the main phase. It was found that in addition to Cu, at least Nd, Pr, Fe, and Co existed in any of the R-rich phases included in the grain boundary triple points of Examples 1 to 5 and Comparative Example 1. It was confirmed that Co was unevenly distributed together with Cu in any of the R-rich phases contained in the triple boundary points of Examples 1 to 5 and Comparative Example 1. It was confirmed that the Co content in the R-rich phase contained in the grain boundary triple points of Examples 1 to 5 and Comparative Example 1 was higher than that of the main phase. In the process of forming a sintered body by firing the compact, Co is precipitated in the grain boundary phase, and Co is moved from the inside of the magnet in a form induced by the diffusion of Cu and eutectoid into the R-Cu rich phase. It is guessed. As a result of analysis by EPMA, it was confirmed that Cu tends to diffuse into the R-rich phase at the grain boundary triple point.

レーザー照射型誘導結合プラズマ質量分析（Ｌａｓｅｒ Ａｂｌａｔｉｏｎ Ｉｎｄｕｃｔｉｖｅｌｙ Ｃｏｕｐｌｅｄ Ｐｌａｓｍａ Ｍａｓｓ Ｓｐｅｃｔｒｏｍｅｔｒｙ：ＬＡ−ＩＣＰ−ＭＳ）により、各希土類磁石を分析した。ＬＡ−ＩＣＰ−ＭＳによる分析では、希土類磁石の断面に対して２０μｍピッチでマッピング測定を行い、磁石表面からＣｕの拡散距離を測定した。ＬＡ−ＩＣＰ−ＭＳの結果、実施例１では、希土類磁石の外表面からの深さが０〜１．２ｍｍである領域にＣｕが拡散し、その領域におけるＣｕの濃度が高くなっていることが確認された。実施例２では、希土類磁石の外表面からの深さが０〜３００μｍである領域にＣｕが拡散し、その領域におけるＣｕの濃度が高くなっていることが確認された。実施例３では、希土類磁石の外表面からの深さが０〜１５０μｍである領域にＣｕが拡散し、その領域におけるＣｕの濃度が高くなっていることが確認された。実施例４では、希土類磁石の外表面からの深さが０〜４０μｍである領域にＣｕが拡散し、その領域におけるＣｕの濃度が高くなっていることが確認された。実施例５では、希土類磁石の外表面からの深さが０〜４００μｍである領域にＣｕが拡散し、その領域におけるＣｕの濃度が高くなっていることが確認された。   Each rare earth magnet was analyzed by laser irradiation type Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). In the analysis by LA-ICP-MS, mapping measurement was performed at a pitch of 20 μm on the cross section of the rare earth magnet, and the diffusion distance of Cu from the magnet surface was measured. As a result of LA-ICP-MS, in Example 1, Cu diffuses into a region where the depth from the outer surface of the rare earth magnet is 0 to 1.2 mm, and the concentration of Cu in that region is high. confirmed. In Example 2, it was confirmed that Cu diffused into a region where the depth from the outer surface of the rare earth magnet was 0 to 300 μm, and the concentration of Cu in that region was high. In Example 3, it was confirmed that Cu diffused into a region where the depth from the outer surface of the rare earth magnet was 0 to 150 μm, and the concentration of Cu in the region was high. In Example 4, it was confirmed that Cu diffused into a region where the depth from the outer surface of the rare earth magnet was 0 to 40 μm, and the concentration of Cu in the region was high. In Example 5, it was confirmed that Cu diffused into a region where the depth from the outer surface of the rare earth magnet was 0 to 400 μm, and the concentration of Cu in that region was high.

[耐食性の評価]
実施例１〜５及び比較例１の各希土類磁石の耐食性をプレッシャークッカーテスト（Ｐｒｅｓｓｕｒｅ Ｃｏｏｋｅｒ Ｔｅｓｔ：ＰＣＴ）により評価した。ＰＣＴでは、２気圧、温度１２０℃、湿度１００％ＲＨである環境下に各希土類磁石を設置してから２００時間後及び５００時間後の各希土類磁石の重量の減少量を測定した。各希土類磁石の単位表面積あたりの重量減少量（単位：ｍｇ／ｃｍ２）を表２に示す。 [Evaluation of corrosion resistance]
The corrosion resistance of each of the rare earth magnets of Examples 1 to 5 and Comparative Example 1 was evaluated by a pressure cooker test (PCT). In PCT, the amount of decrease in the weight of each rare earth magnet was measured 200 hours and 500 hours after each rare earth magnet was installed in an environment of 2 atm, temperature 120 ° C., and humidity 100% RH. Table 2 shows the weight loss (unit: mg / cm 2 ) per unit surface area of each rare earth magnet.

Figure 2011199183
Figure 2011199183

実施例１〜５の各希土類磁石は、比較例１に比較して耐食性に優れていることが確認された。   Each of the rare earth magnets of Examples 1 to 5 was confirmed to be excellent in corrosion resistance as compared with Comparative Example 1.

実施例１及び比較例１の各希土類磁石を、１００℃、０．１ＭＰａの水素雰囲気中に放置する試験を行った。比較例１では、１００秒経過後に希土類磁石が水素を吸蔵したことによって水素分圧が低下し始めた。一方、実施例１では、３００秒経過後も希土類磁石が水素を吸蔵せず、水素分圧が低下しなかった。   Each rare earth magnet of Example 1 and Comparative Example 1 was tested in a hydrogen atmosphere at 100 ° C. and 0.1 MPa. In Comparative Example 1, the hydrogen partial pressure began to decrease after the rare earth magnet occluded hydrogen after 100 seconds. On the other hand, in Example 1, the rare earth magnet did not absorb hydrogen after 300 seconds, and the hydrogen partial pressure did not decrease.

［磁気特性の評価］
実施例１〜５及び比較例１，２の各希土類磁石の残留磁束密度（Ｂｒ）及び保磁力（ＨｃＪ）を測定した。各希土類磁石のＢｒ（単位：Ｔ）及びＨｃＪ（単位：ｋＡ／ｍ）を表３に示す。 [Evaluation of magnetic properties]
The residual magnetic flux density (Br) and the coercive force (HcJ) of each of the rare earth magnets of Examples 1 to 5 and Comparative Examples 1 and 2 were measured. Table 3 shows Br (unit: T) and HcJ (unit: kA / m) of each rare earth magnet.

Figure 2011199183
Figure 2011199183

実施例１〜５の各希土類磁石のいずれも充分な残留磁束密度及び保磁力を有していることが確認された。   It was confirmed that each of the rare earth magnets of Examples 1 to 5 has sufficient residual magnetic flux density and coercive force.

４・・・結晶粒子、６・・・粒界三重点、３０・・・ステータ、３２・・・コイル、４０，Ａ・・・表面部、５０・・・ロータ、５２・・・コア、１００・・・希土類磁石、２００・・・回転機、Ｄ・・・表面部の厚さ（Ｃｕの拡散距離）。
4 ... Crystal grain, 6 ... Grain boundary triple point, 30 ... Stator, 32 ... Coil, 40, A ... Surface part, 50 ... Rotor, 52 ... Core, 100 ... Rare earth magnet, 200 ... Rotating machine, D ... Thickness of surface portion (Cu diffusion distance).

Claims (4)

希土類元素Ｒを含むＲ−Ｆｅ−Ｂ系合金の結晶粒子群を備える希土類磁石であって、
前記希土類磁石の表面部に位置する前記結晶粒子の粒界三重点に含まれるＲリッチ相に存在するＣｕの原子数が[Ｃｕ]であり、前記Ｒリッチ相に存在するＦｅの原子数が[Ｆｅ]であり、前記Ｒリッチ相に存在するＲの原子数が[Ｒ]であるとき、
[Ｃｕ]＞[Ｆｅ]であり、
[Ｃｕ]／[Ｒ]＞０．５である、
希土類磁石。 A rare earth magnet comprising a crystal particle group of an R—Fe—B alloy containing a rare earth element R,
The number of Cu atoms present in the R-rich phase contained in the grain boundary triple point of the crystal grains located on the surface portion of the rare earth magnet is [Cu], and the number of Fe atoms present in the R-rich phase is [ Fe], and when the number of R atoms present in the R-rich phase is [R],
[Cu]> [Fe],
[Cu] / [R]> 0.5,
Rare earth magnet. 前記結晶粒子におけるＣｕの含有率が０．０５原子％以下である、
請求項１に記載の希土類磁石。 The content of Cu in the crystal particles is 0.05 atomic% or less,
The rare earth magnet according to claim 1. 前記希土類磁石全体に占める前記結晶粒子群の割合が８５体積％以上である、
請求項１又は２に記載の希土類磁石。 The proportion of the crystal particle group in the entire rare earth magnet is 85% by volume or more,
The rare earth magnet according to claim 1 or 2. 請求項１〜３のいずれか一項に記載の希土類磁石を備える回転機。
A rotating machine comprising the rare earth magnet according to any one of claims 1 to 3.
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